1. Field of the Invention
The invention relates to optical waveguides which are suitable for the transmission of light signals. These optical waveguides have a high heat resistance.
2. Description of the Prior Art
Filamentous optical waveguides consist of a transparent material and are composed in most cases of a core and a shell, the core material always having a refractive index higher than that of the shell material. In addition, the core material and shell material should absorb as little light as possible.
The polymeric materials hitherto employed most frequently for optical waveguides are homopolymers and copolymers of methyl methacrylate. Whereas halogen-containing polymers have also been employed for the core, fluorine-containing polymers have hitherto been used for the shell, because they have a lower refractive index. To reduce the light absorption, it has also already been proposed to replace the hydrogen atoms in the monomers and polymers by deuterium.
Copolymers of trifluorometharcylate and styrene or substituted styrene, for example halogen-containing styrene, are know (cf. German Offenlegungsschrift, 3,518,617). The copolymers are used, inter alia, as the shell material for optical fibers.
An optical waveguide has also been described, the core material of which is prepared by block polymerization of, inter alia, halogenated aryl metharcylate, for example pentafluorophenyl metharcylate (cf. Japanese Published application 60-242,404). Copolymers of vinylindene fluoride, tetralfuoroethylene and hexafluoropropylene are used as the shell material.
However, the abovementioned polymers do not give optical waveguides with a heat resistance adequate for certain fields of application.